1. Field of the Invention
The present invention relates mainly to a reclining apparatus of a vehicle seat. More specifically, the present invention relates to structural reinforcement of a housing member that is a constituent element of a reclining apparatus.
2. Description of the Related Art
Reclining apparatuses are known in which a seat back is supported so as to be inclinable relative to a seat, and in which the seat back can be switched between a locked state and an unlocked state. Such a reclining apparatus is disclosed in JP 2005-312891A, for example. Below, a simple description of the technical content of JP 2005-312891A is given, citing the reference numerals used in JP 2005-312891A.
The reclining apparatus according to JP 2005-312891A is provided with a fixed-side housing 11 and a rotating-side housing 12 whose outer shell forms a disk-like shape, and the reclining apparatus is configured by fitting the housings 11 and 12 together facing each other. The fixed-side housing 11 is installed to a seat cushion-side of a vehicle seat, and the rotating-side housing 12 is installed to a seat back-side of the vehicle seat. A storage space is secured between the fixed-side housing 11 and the rotating-side housing 12, which are disposed facing each other, and in this storage space, a plurality of slide poles 15 (also referred to as “locking gears”), a rotating cam 16, and other members are stored.
A ring-shaped ratchet 12c (corresponding to an “internal gear”) that has inner teeth on its inner circumferential side is provided in the rotating-side housing 12. On the other hand, outer teeth that can engage with the inner teeth of the ring-shaped ratchet 12c are provided at the end of each slide pole 15. The rotating cam 16 is disposed in a center region of the group of slide poles 15 in order to push each of the plurality of slide poles 15 toward the inner teeth of the ratchet 12c. By engaging or separating the outer teeth of each slide pole 15 with/from the inner teeth of the ratchet 12c according to operation of the rotating cam 16, a locked or unlocked state of the seat back is realized.
As shown in FIG. 7 (reproduced as FIG. 7A in the present application) of JP 2005-312891A, several guide portions 30 are formed integrated with the fixed-side housing 11. These guide portions 30 are for holding a slide pole 15 that is disposed between two adjacent guide portions 30, such that the slide pole 15 can move in the radial direction of the fixed-side housing 11, and in each guide portion 30, receiving wall faces 31 that make contact with the slide pole 15 are formed. The receiving wall faces 31 function both as guide faces that guide advancement/withdrawal of the slide pole 15 relative to the ratchet 12c, and as regulating faces that regulate movement in the circumferential direction of the slide pole 15. Moreover, in each guide portion 30, two stress concentrating portions 33 provided in one receiving wall face 31 of the guide portion 30, and a flat portion 34 positioned between the two stress concentrating portions 33 in roughly the center of that receiving wall face 31, are provided.
The fixed-side housing 11 of JP 2005-312891A is obtained by press-molding a metal plate as material, and each guide portion 30 is formed in an integrated manner by press-molding from one face side of the fixed-side housing 11 toward the rotating-side housing 12. Consequently, as shown in FIG. 7B reflecting the right angle edge shape of the press-molding die, the cross-sectional structure is such that the guide portion 30 and a main body side portion 41 that is continuous with the guide portion 30 are offset with a height difference in the thickness direction (the vertical direction in FIG. 7B) of the fixed-side housing 11. As a result, the thickness of a connecting portion 42 positioned directly below the receiving wall face 31 (that is, a connecting portion 42 that connects the guide portion 30 and the main body side portion 41 that is continuous with the guide portion 30) is very small. Therefore, when a large load reaches to the receiving wall face 31 via the slide pole 15 during a vehicle collision, there is a risk that the thin connecting portion 42 directly below the receiving wall face 31 will break.
Also, the object of the technology in JP 2005-312891A is to, by adopting a structure in the receiving wall face 31 of the guide portion 30 that includes the two stress concentrating portions 33 and the flat portion 34 that is recessed relative to the stress concentrating portions, reduce the force necessary for operation of the slide pole 15, thus insuring durability against the load when the seat back has been inclined. However, there is the drawback that when a surface pressure with which the slide pole 15 presses against the receiving wall face 31 (in particular the stress concentrating portions 33) of the guide portion 30 is extremely high, for example such as during a vehicle collision, there is a high risk that the thin connecting portion 42 will break.